<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
<script>
  //  返回一个obj结构，展示age
  const obj = {
    name: {
      msg: {
        age: 18
      }
    }
  }

  // 判断
  console.log(obj.name.msg.age)
  console.log(obj?.name?.msg?.age)

  // const name = [
  //   {
  //     name: '23'
  //   }
  // ]

  // let const
  //

  // if (obj && obj.name && obj.name.msg) {
  //   console.log(obj.name.msg.age)
  // }


  //  webpack里面loader和plugin的区别？

</script>
</body>
</html>
